Showing papers on "Offset (computer science) published in 2018"

Box2Pix: Single-Shot Instance Segmentation by Assigning Pixels to Object Boxes

Abstract: The task of semantic instance segmentation has gained a large interest within academia as well as industry, especially in the context of autonomous driving. While several published approaches achieve very strong results, only few of them achieve frame rates that are sufficient for the automotive domain. We present an approach that achieves competitive results on the Cityscapes [1] and KITTI [2] datasets, while being twice as fast as any other existing approach. Our method relies on a single fully-convolutional network (FCN [3]) predicting object bounding boxes, as well as pixel-wise semantic object classes and an offset vector pointing to corresponding object centers. Using those outputs, we present an efficient and simple post-processing that assigns each object pixel to its best matching object detection, resulting in an instance segmentation obtained at real-time speeds.

Inverter-Current-Feedback Resonance-Suppression Method for LCL-Type DG System to Reduce Resonance-Frequency Offset and Grid-Inductance Effect

Abstract: For the LCL-type grid-connected distributed generation system, the grid-current-feedback active damping (GCFAD) methods have a conflict between the resonance-suppression ability and harmonic-currents amplification. For this, an inverter-current-feedback reso-nance-suppression (ICFRS) method without additional sensors is proposed to reduce resonance-frequency offset and grid-inductance effect due to its unattenuated damping characteristic under high-frequency bandwidth. By analyzing two types of equivalent impedance models of ICFRS and GCFAD with a high-pass filter (HPF), GCFAD can suppress the resonance peak well only with a large resonance-frequency offset and might result in a narrow control bandwidth. However, ICFRS can suppress the resonance peak well with smaller resonance-frequency offset and maintain a high power quality compared with GCFAD. Considering the influence of control delay and grid inductance, the positive/negative critical point of an equivalent virtual resistance of ICFRS derived in the interval of [1/6, 1/3) is obtained, and a robust ICFRS is further proposed to improve system stability by maintaining a positive resistance regardless of grid-inductance variation. The stable-state and dynamic properties of the overall system are analyzed in detail in this paper, and its proper control parameters are selected without a complicated trial. Finally, simulation and experimental results verify the validity of the proposed method.

The impact performance of honeycomb-filled structures under eccentric loading for subway vehicles

Abstract: When a train collision occurs, it is impossible for the vehicle to produce a completely axial collision. To improve the energy absorption performance of the energy-absorbing structure under an eccentric collision, in this paper, a FE model of the energy absorption structure for subway vehicles was created and validated by experimental data. Based on the validated FE model, the collision performances under a vertical offset of 0–80 mm and a horizontal offset of 0–40 mm are studied via simulation. The results show that the original structure is prone to instability when the horizontal offset is greater than 30 mm, so it is necessary to perform an optimization. Based on the bending strength, the cross-sectional shape of the guide was changed. The results show that there is no instability phenomenon in the improved structure I1 under all horizontal offsets. Under the horizontal offset of 40 mm, compared with the original structure, the energy absorption increased by 175.89%, and the peak force also increased by 14.46%. Based on the concept of gradient material, the honeycomb strength in the structure is changed into a gradient distribution, and the results show that the improved structure I2 also did not show any instability phenomenon under all horizontal offsets. Under the horizontal offset of 40 mm, compared with the original structure, the energy absorption increased by 171.88% and the peak force decreased by 1.92% at the same time.

Performance Analysis for Channel Estimation With 1-Bit ADC and Unknown Quantization Threshold

Abstract: In this work, the problem of signal parameter estimation from measurements acquired by a low-complexity analog-to-digital converter (ADC) with 1-bit output resolution and an unknown quantization threshold is considered. Single-comparator ADCs are energy-efficient and can be operated at ultrahigh sampling rates. For analysis of such systems, a fixed and known quantization threshold is usually assumed. In the symmetric case, i.e., zero hard-limiting offset, it is known that in the low signal-to-noise ratio (SNR) regime the signal processing performance degrades moderately by ${2}/{\pi }$ ( $-\text{1.96}$ dB) when comparing to an ideal $\infty$ -bit converter. Due to hardware imperfections, low-complexity 1-bit ADCs will, in practice, exhibit an unknown threshold different from zero. Therefore, we study the accuracy that can be obtained with received data processed by a hard-limiter with unknown quantization level by using asymptotically optimal channel estimation algorithms. To characterize the estimation performance of these nonlinear algorithms, we employ analytic error expressions for different setups while modeling the offset as a nuisance parameter. In the low SNR regime, we establish the necessary condition for a vanishing loss due to missing offset knowledge at the receiver. As an application, we consider the estimation of single-input single-output wireless channels with intersymbol interference and validate our analysis by comparing the analytic and experimental performance of the studied estimation algorithms. Finally, we comment on the extension to multiple-input multiple-output channel models.

Adaptive coordinated traffic control for stochastic demand

Abstract: Traffic arrivals at intersections are inherently uncertain. This paper develops an adaptive coordinated traffic control approach in the presence of traffic demand uncertainty via the notion of Phase Clearance Reliability (PCR). We propose a method to adjust signal offset adaptively in order to deal with stochastic demands. Based on the cumulative queuing regime, this study first extends the delay models, which are usually formulated for isolated intersections, to the case of coordinated intersections by explicitly incorporating the effects of residual queue and signal offset. Two types of delay formulae are considered regarding two different arrival patterns on the intersection approaches, i.e. coordinated approach and non-coordinated approach delay. We then formulate a two-stage stochastic program to optimize (minimize) the expected total delay for the coordinated control system. The base timing plan is derived at the first stage, while the recourse decisions of adaptive signal offsets are made at the second stage to compensate for the overflow effects. Furthermore, a PCR-based gradient solution algorithm is developed to solve the two-stage stochastic program. The case study on a test network confirms the effectiveness of the proposed PCR-based control method in terms of minimizing average total delay. The optimal control performance stems partly from the short cycle lengths, which are attributed to the fact that part of the random arrivals are addressed by adjusting the signal offsets adaptively. This effective use of signal offset provides a new perspective for designing coordinated signal control plans.

Design of an advanced PLL for accurate phase angle extraction under grid voltage HIHs and DC offset

Abstract: The presence of direct current (DC) offset and harmonics–interharmonics (HIHs) in grid voltage input signal of phase-locked loop (PLL) results in inaccurate controller response. The inaccuracies are due to the low- and high-frequency oscillations that appear in the PLL estimated phase, amplitude and frequency. The suppression of fundamental frequency oscillations caused by DC offset (DO) in the input voltage signal must be carried out without compromising the dynamic response of the system. The use of low-pass filters, for example, results in undesirable, slow response. This study proposes an accurate and fast decoupling of fundamental frequency oscillations using a mathematic-cancellation decoupling cell. Higher-frequency oscillations generated by HIHs are eliminated by a different harmonic compensation network (HCN) that is also proposed in this study. The performance of conventional techniques is limited because they eliminate only specifically selected harmonics. The proposed PLL, however, eliminates any number of HIHs present in the grid with the least computational complexity and without any prior knowledge. Furthermore, its advanced features provide accurate synchronisation under any abnormal grid condition at the lowest computational complexity when compared with the existing state-of-the-art PLLs. The advanced performance of the proposed HIHDO-PLL is verified through simulation and experimental results.

Line-scan spectrum-encoded imaging by dual-comb interferometry

Abstract: Herein, the method of spectrum-encoded dual-comb interferometry is introduced to measure a three-dimensional (3-D) profile with absolute distance information. By combining spectral encoding for wavelength-to-space mapping, dual-comb interferometry for decoding and optical reference for calibration, this system can obtain a 3-D profile of an object at a stand-off distance of 114 mm with a depth precision of 12 μm. With the help of the reference arm, the absolute distance, reflectivity distribution, and depth information are simultaneously measured at a 5 kHz line-scan rate with free-running carrier-envelope offset frequencies. To verify the concept, experiments are conducted with multiple objects, including a resolution test chart, a three-stair structure, and a designed “ECNU” letter chain. The results show a horizontal resolution of ∼22 μm and a measurement range of 1.93 mm.

Role of contact work function, back surface field, and conduction band offset in Cu

Abstract: We employ simulation based approach for enhancing the efficiency of Cu2ZnSnS4 (CZTS) based solar cells. Initial benchmarking of simulation with the experimentally reported solar cell in literature is performed by incorporating a suitable defect model. We then explore the effects of (a) conduction band offset (CBO) at CZTS/CdS junction, (b) back surface field (BSF) due to an additional layer with higher carrier density, and (c) high work function back contact. Efficiency is observed to improve by about 70% upon optimizing the above three parameters. We also observe that utilizing BSF in the configuration can reduce the high work function requirement of the back contact. A work function of 5.2 eV (e.g., using Ni), a BSF layer (e.g., using SnS), and a CBO of 0.1 eV (e.g., using ZnS) constitute an optimal configuration.

Analysis and Background Self-Calibration of Comparator Offset in Loop-Unrolled SAR ADCs

Abstract: In conventional charge redistribution successive approximation register (SAR) ADCs that use a single comparator, the comparator offset causes no distortion but a dc shift in the transfer curve. In loop-unrolled (LU) SAR ADCs, on the other hand, mismatched comparator offset voltages introduce input-level-dependent errors to the conversion result, which deteriorates the linearity and limits the resolution. Still, the literature lacks a quantitative analysis on this phenomenon, and the resolution of most reported SAR ADCs of this kind, until recently, has been limited to 6 bit. In this paper, we analyze the effects of comparator offset voltage mismatch in LU-SAR ADCs, and establish the quantitative relation between individual offsets and the signal-to-noise-and-distortion ratio (SNDR) and the effective-number-of-bits. A statistical linearity model is proposed for yield estimation. Finally, an on-line deterministic calibration technique for auto-zeroing dynamic comparator offset is presented to treat the offsets mismatch and improve linearity. A 150-MS/s 8-bit LU-SAR ADC is fabricated in a 130-nm CMOS technology to validate the concept. The measured result shows that the calibration improves the SNDR from 33.7 to 42.9 dB. The ADC consumes $640~\mu \text{W}$ from a 1.2-V supply with a figure-of-merit of 37.5 fJ/conv-step.

A data-driven amplitude variation with offset inversion method via learned dictionaries and sparse representation

Abstract: Amplitude variation with offset (AVO) inversion is a typical ill-posed inverse problem. To obtain a stable and unique solution, regularization techniques relying on mathematical models from...

Integration of PSI, MAI, and Intensity-Based Sub-Pixel Offset Tracking Results for Landslide Monitoring with X-Band Corner Reflectors—Italian Alps (Corvara)

Abstract: This paper presents an analysis of the integration between interferometric and intensity-offset tracking-based SAR remote sensing for landslide hazard mitigation in the Italian Alps. Despite the advantages of Synthetic Aperture Radar Interferometry (InSAR) methods for quantifying landslide deformation, some limitations remain. The temporal decorrelation, the 1-D Line Of Sight (LOS) observation restriction, the high velocity rate and the multi-directional movement properties make it difficult to monitor accurately complex landslides in areas covered by vegetation. Therefore, complementary and integrated approaches, such as offset tracking-based techniques, are needed to overcome these InSAR limitations for monitoring ground surface deformations. As sub-pixel offset tracking is highly sensitive to data spatial resolution, the latest generations of SAR sensors, such as TerraSAR-X and COSMO-SkyMed, open interesting perspective for a more accurate hazard assessment. In this paper, we consider high-resolution X-band data acquired by the COSMO-SkyMed (CSK) constellation for Permanent Scatterers Interferometry (PSI), Multi-Aperture Interferometry (MAI) and offset tracking processing. We analyze the offset tracking techniques considering area and feature-based matching algorithms to evaluate their applicability to CSK data by improving sub-pixel offset estimations. To this end, PSI and MAI are used for extracting LOS and azimuthal displacement components. Then, four well-known area-based and five feature-based matching algorithms (taken from computer vision) are applied to 16 X-band corner reflectors. Results show that offset estimation accuracy can be considerably improved up to less than 3% of the pixel size using the combination of the different feature-based detectors and descriptors. A sensitivity analysis of these techniques applied to CSK data to monitor complex landslides in the Italian Alps provides indications on advantages and disadvantages of each of them.

Angles-only initial relative orbit determination algorithm for non-cooperative spacecraft proximity operations

Abstract: This research furthers the development of a closed-form solution to the angles-only initial relative orbit determination problem for non-cooperative target close-in proximity operations when the camera offset from the vehicle center-of-mass allows for range observability. In previous work, the solution to this problem had been shown to be non-global optimal in the sense of least square and had only been discussed in the context of Clohessy-Wiltshire. In this paper, the emphasis is placed on developing a more compact and improved solution to the problem by using state augmentation least square method in the context of the Clohessy-Wiltshire and Tschauner-Hempel dynamics, derivation of corresponding error covariance, and performance analysis for typical rendezvous missions. A two-body Monte Carlo simulation system is used to evaluate the performance of the solution. The sensitivity of the solution accuracy to camera offset, observation period, and the number of observations are presented and discussed.

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

Abstract: This paper presents an eddy-current sensor (ECS) interface intended for sub-nanometer (sub-nm) displacement sensing in hi-tech applications. The interface employs a 126-MHz excitation frequency to mitigate the skin effect, and achieve high resolution and stability. An efficient on-chip sensor offset compensation scheme is introduced which removes sensor-offset proportional to the standoff distance. To assist in the ratiometric suppression of noise and drift of the excitation oscillator, the ECS interface consists of a highly linear amplitude demodulation scheme that employs passive capacitors for voltage-to-current (V2I) conversion. Using a printed circuit board-based pseudo-differential ECS, stability tests were performed which demonstrated a thermal drift of $\sqrt {\mathrm{ Hz}}$ which corresponds to a displacement resolution of 0.6 nm in a 2-kHz noise bandwidth. The ECS interface is fabricated in TSMC 0.18- $\mu \text{m}$ CMOS technology and dissipates only 19.8 mW from a 1.8-V supply.

The optimal mating distance resulting from heterosis and genetic incompatibility

Abstract: Theory predicts that the fitness of an individual is maximized when the genetic distance between its parents (i.e., mating distance) is neither too small nor too large. However, decades of research have generally failed to validate this prediction or identify the optimal mating distance (OMD). Respectively analyzing large numbers of crosses of fungal, plant, and animal model organisms, we indeed find the hybrid phenotypic value a humped quadratic polynomial function of the mating distance for the vast majority of fitness-related traits examined, with different traits of the same species exhibiting similar OMDs. OMDs are generally slightly greater than the nucleotide diversities of the species concerned but smaller than the observed maximal intraspecific genetic distances. Hence, the benefit of heterosis is at least partially offset by the harm of genetic incompatibility even within species. These results have multiple theoretical and practical implications for speciation, conservation, and agriculture.

Improved Holistic Analysis of Rayleigh Waves for Single- and Multi-Offset Data: Joint Inversion of Rayleigh-Wave Particle Motion and Vertical- and Radial-Component Velocity Spectra

Abstract: Rayleigh waves often propagate according to complex mode excitation so that the proper identification and separation of specific modes can be quite difficult or, in some cases, just impossible. Furthermore, the analysis of a single component (i.e., an inversion procedure based on just one objective function) necessarily prevents solving the problems related to the non-uniqueness of the solution. To overcome these issues and define a holistic analysis of Rayleigh waves, we implemented a procedure to acquire data that are useful to define and efficiently invert the three objective functions defined from the three following “objects”: the velocity spectra of the vertical- and radial-components and the Rayleigh-wave particle motion (RPM) frequency-offset data. Two possible implementations are presented. In the first case we consider classical multi-offset (and multi-component) data, while in a second possible approach we exploit the data recorded by a single three-component geophone at a fixed offset from the source. Given the simple field procedures, the method could be particularly useful for the unambiguous geotechnical exploration of large areas, where more complex acquisition procedures, based on the joint acquisition of Rayleigh and Love waves, would not be economically viable. After illustrating the different kinds of data acquisition and the data processing, the results of the proposed methodology are illustrated in a case study. Finally, a series of theoretical and practical aspects are discussed to clarify some issues involved in the overall procedure (data acquisition and processing).

Decision Fusion of D-InSAR and Pixel Offset Tracking for Coal Mining Deformation Monitoring

Abstract: Ground surface subsidence is a universal phenomenon in coal mining areas which can cause serious damage to the surrounding environment. In this paper, we consider the use of differential interferometric synthetic aperture radar (D-InSAR), multi-temporal InSAR (MT-InSAR), and the pixel offset tracking technique to monitor the surface deformation of a coal mining area. In this study, we use the two-pass D-InSAR method to generate 19 interferometric image pairs from 20 TerraSAR-X SpotLight images. The results show that D-InSAR can be used to obtain high accuracy surface deformation in the mining areas where there is no high gradient deformation, and the pixel offset tracking method offers advantages in those areas where high gradient deformation is found, but its performance is not stable. This means that the unilateral use of these technologies cannot obtain reliable subsidence information in mining areas. Therefore, it is essential to find a new way to integrate the respective advantages of these different methods. In this paper, a new fusion method combining the D-InSAR result with the offset tracking result based on a spatial decorrelation distribution map is proposed to obtain the subsidence results in a mining area. To ensure the reliability of the results, a decision rule is proposed for the spatial decorrelation distribution map, which is generated manually by union analysis in ArcGIS. In the experiments, the mean absolute error of the fusion result is 0.0748 m, while that of D-InSAR is 0.1890 m, and that of offset tracking is 0.1358 m. It is therefore clear that the proposed fusion method is more reliable and more accurate than the use of individual methods, and it may be able to serve as a reference in mining subsidence monitoring.

Method for sending and receiving reference signal, network device, terminal device and system

Abstract: Provided in the application are a method for sending and receiving a reference signal, a network device, a terminal device and a system The method, the network device, the terminal device and the system are applicable to SRS resource configuration in NR The method comprises the steps that: the terminal device sends an SRS according to the position of a starting subcarrier transmitting the sounding reference signal SRS; wherein the position of the starting subcarrier transmitting the SRS is determined by the offset of a sounding region, the offset of the sounding region indicates the amount of resource that the starting subcarrier of the sounding region offsets relative to the starting subcarrier of a bandwidth portion BWP of the terminal device, and the sounding region is a resource for transmitting the SRS

Optimal Design of Point-Focusing Shear Vertical Wave Electromagnetic Ultrasonic Transducers Based on Orthogonal Test Method

Abstract: The lower conversion efficiency is the main drawback of electromagnetic acoustic transducers (EMATs) compared with other transducers, which limits their use in many industrial applications In this paper, for enhancing the performance of point-focusing shear vertical wave EMATs (PFSV-EMATs), 18 orthogonal tests with seven factors and three levels are conducted through finite-element simulations First, the degree of seven factors on the signal amplitude, axial focus offset, and radial focus offset is obtained by range analysis and compared It indicates that the effect of the liftoff distance and the exciting current on signal amplitude is the largest, while the effect of the inner radius of concentric meander-line coils on the axial and radial focal offset is the largest Then, the influence degree of various factors on test results is analyzed at frequencies of 15, 2, and 25 MHz, showing that the relatively low frequency, ie, the sparser coil spacing, is favorable for signal amplitude and detrimental for point-focusing ability Finally, experiments are carried out to verify the validation of optimization results, which indicates that the increased signal amplitude of 8878%, smaller axial focus offset, and zero radial focus offset can be achieved by the optimized PFSV-EMAT, which has the improved signal amplitude and point-focusing behavior, compared with the non-optimized one

Gravity mode offset and properties of the evanescent zone in red-giant stars

Abstract: The wealth of asteroseismic data for red-giant stars and the precision with which these data have been observed over the last decade calls for investigations to further understand the internal structures of these stars. The aim of this work is to validate a method to measure the underlying period spacing, coupling term and mode offset of pure gravity modes that are present in the deep interiors of red-giant stars. We subsequently investigate the physical conditions of the evanescent zone between the gravity mode cavity and the pressure mode cavity. We implement an alternative mathematical description to analyse observational data and to extract the underlying physical parameters that determine the frequencies of mixed modes. This description takes the radial order of the modes explicitly into account, which reduces its sensitivity to aliases. Additionally, and for the first time, this method allows us to constrain the gravity mode offset for red-giant stars. We determine the period spacing and the coupling term for the dipole modes within a few percent of literature values. Additionally, we find that the gravity mode offset varies on a star by star basis and should not be kept fixed in the analysis. Furthermore, we find that the coupling factor is logarithmically related to the physical width of the evanescent region normalised by the radius at which the evanescent zone is located. Finally, the local density contrast at the edge of the core of red giant branch models shows a tentative correlation with the offset. (abstract abriged)

Fundamental Mode Orthogonal Fluxgate Magnetometer Applicable for Measurements of DC and Low-Frequency Magnetic Fields

Abstract: Compatibility of low noise characteristic and offset stability is essential for a magnetometer to be applicable for measurements of dc and low-frequency magnetic fields. Fundamental mode orthogonal fluxgate (FM-OFG) magnetometer has advantages in its compact design and low noise characteristic, whereas its disadvantage is the offset drift which is unacceptably large for such measurement. An effective technique called bias switching has been proposed to suppress and stabilize the offset of open-loop FM-OFG magnetometers, yet when it is adopted with a feedback configuration to obtain better linearity, it increases noises attributed to the convergence process. In this paper, we present a design of sensor driving electronics of FM-OFG magnetometers to solve this problem and achieve compatibility of low noise and stable offset characteristics with a feedback configuration. The efficacy of the design was verified through various performance evaluations.

Three-dimensional super-resolution correlation-differential confocal microscopy with nanometer axial focusing accuracy

Abstract: We present a correlation-differential confocal microscopy (CDCM), a novel method that can simultaneously improve the three-dimensional spatial resolution and axial focusing accuracy of confocal microscopy (CM). CDCM divides the CM imaging light path into two paths, where the detectors are before and after the focus with an equal axial offset in opposite directions. Then, the light intensity signals received from the two paths are processed by the correlation product and differential subtraction to improve the CM spatial resolution and axial focusing accuracy, respectively. Theoretical analyses and preliminary experiments indicate that, for the excitation wavelength of λ = 405 nm, numerical aperture of NA = 0.95, and the normalized axial offset of uM = 5.21, the CDCM resolution is improved by more than 20% and more than 30% in the lateral and axial directions, respectively, compared with that of the CM. Also, the axial focusing resolution important for the imaging of sample surface profiles is improved to 1 nm.

Evaluation of Cursor Offset on 3D Selection in VR

Abstract: Object selection in a head-mounted display system has been studied extensively. Although most previous work indicates that users perform better when selecting with minimum offset added to the cursor, it is often not possible to directly select objects that are out of arm's reach. Thus, it is not clear whether offset-based techniques will result in improved overall performance. Moreover, due to the difference in muscle requirements of arm and shoulder between a hand-held device and a motion capture device, selection performance may be affected by factors related to ergonomics of the input device. In order to explore these uncertainties, we conduct a user study to evaluate the effects of four virtual cursor offset techniques on 3D object selection performance using Fitts' model and ISO 9241-9 standard while comparing two input devices in a head-mounted display. The results show that selection with No Offset is most efficient when the target is within reach. When the target is out of reach, Linear Offset outperforms Fixed-Length Offset and Go-Go Offset on movement time, error rate and effective throughput, as well as subjective preference evaluation. Overall, the Razer Hydra controller provides better and more stable selection performance than Leap Motion.

System and calibration, registration, and training methods

Abstract: One variation of a method for manipulating a multi-link robotic arm includes: accessing a virtual model of the target object; extracting an object feature representing the target object from the virtual model; at the robotic arm, scanning a field of view of an optical sensor for the object feature, the optical sensor arranged on a distal end of the robotic arm proximal an end effector; in response to detecting the object feature in the field of view of the optical sensor, calculating a physical offset between the target object and the end effector based on a position of the object feature in the field of view of the optical sensor and a known offset between the optical sensor and the end effector; and driving a set of actuators in the robotic arm to reduce the physical offset.

Robust Downlink Transmission: An Offset-Based Single-Rate-Splitting Approach

Abstract: We consider a multi-user multiple-input single-output downlink system that provides each user with a prespecified level of quality-of-service The rate-splitting (RS) approach to this problem involves splitting the messages of each user into common and private portions that are transmitted in superposition and decoded sequentially By adjusting the rates of each portion, the RS approach is able to mitigate the interference that conventional linear beamforming (CLB) schemes incur when users have channels that are closely aligned However, the transmitter design problem for the RS approach can be quite challenging to solve In this paper we develop a single-rate-splitting approach, in which RS is applied only to the user with the channel that is “most aligned” with the other channels This approach greatly reduces the computational cost of RS designs, and admits an offset-based variant that provides robustness to channel estimation errors Despite its simplifications, our simulation results indicate that the proposed approach retains most of the performance advantage of RS transmission over CLB

A New Distance Protection Method Considering TCSC-FCL Dynamic Impedance Characteristics

Abstract: Ignoring the dynamic impedance characteristics of a thyristor-controlled series-capacitor-type fault current limiter (TCSC-FCL) may lead to maloperation/fail-to-trip or slow response of distance protection. To solve the above problem, the TCSC-FCL dynamic impedance analysis model was established. Taking the special operation mode of the TCSC-FCL into account, the time-varying characteristics of the TCSC-FCL during the whole process from the series compensation mode to the current-limiting mode were analyzed. Then, this paper proposed the function expression of dynamic impedance characteristics of the TCSC-FCL and put forward the distance protection setting strategy based on a dynamic offset impedance circle in order to eliminate the influence of TCSC-FCL dynamic impedance characteristics to the distance protection operation. By establishing a typical simulation model including the TCSC-FCL, the correctness of dynamic feature's analytic expression and the distance protection setting strategy is proved with extensive simulation results.